What is the oxidation number of Mn in MnO4 ? Plz note this is MnO4 and NOT KMnO4! Share with your friends Share 0 Bharti Paliwal answered this Dear Student MnO4 is not possible because then the oxidation state of Mn will bex+ 4*(-2) = 0x = +8Mn has 7 electrons in the outermost shell , thus the maximum oxidation state possible for Mn is +7.Thus, the specie must be KMnO4 or MnO4-. -1 View Full Answer